Immaturity of the gastrointestinal tract in preterm and term infants contributes significantly to their morbidity and prolonged hospitalizations; key factors in these adverse effects are difficulties in the provision of nutrition, the need to use parenteral nutrition with its multiple attendant complications, and the slowed rate of somatic growth. The overall objective of this proposal is to characterize the development of human neonatal small intestine by utilizing two indices of development which can be sampled during the routine clinical management of these infants; these are 1) intestinal motility patterns and 2) the release of gastrointestinal peptide after a feed. Prior to our studies, techniques for assessing directly maturation of neonatal intestine have not been available. Using a novel technique to record neonatal small intestinal motility in a safe, reliable manner, we have examined motor activity during fasting and feeding. Preterm infant motility patterns are more immature than those seen in term infants; however, administration of enteral nutrition accelerates maturation of preterm motility patterns. The proposed study will assess in a prospective randomized manner on postnatal days 1, 14, and 28 intestinal motility during fasting and feeding and plasma concentrations of gastrointestinal polypeptides before, during, and after feeding. The aims of this study are 1) to characterize the association of maturation of intestinal motility and intestinal peptide response to feeding; 2) to investigate if early introduction of enteral feedings facilitate earlier intestinal maturation compared to infants who initiate enteral nutrition on day 14; and 3) to determine the role of volume of enteral feedings in intestinal maturation. These studies are of major clinical relevance, they will extend our current knowledge of postnatal development, and could lead to more rational and useful provision of postnatal nutrition. Additionally, they will lay a firm foundation for future studies to investigate the individual roles of specific nutrients on the functional maturation of the human intestine and conversely, how maturation of intestinal motor and peptide responses affect absorption of various nutrients.